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From Ontario, Canada:

I have been Type 1 diabetic for 33 years. I am 39 now. I want to start an exercise program. At what blood sugar level should I not exercise? If my blood sugar is running at 150 should I still exercise? Tell me how come my blood sugar could go up.


It is nice to hear that you want to start an exercise program. Do inform your physician/endocrinologist about your plans to start.

Here are some guidelines put out by the American College of Sport Medicine: If your blood glucose is less than 100 mg/dl, do eat a snack before exercising. The amount of carbohydrate you take in depends upon the length of time you will be engaging in the particular activity as well as the intensity of the activity itself. If your blood glucose is over 250 mg/dl check for ketones. If ketones are present, do not exercise. If your blood glucose is over 400 mg/dl, do not exercise. You are not in good control.

To answer the second part of your question, blood glucose can go up for two reasons:

  1. If you exercise very strenuously, your blood glucose level may rise due to the stress hormone adrenaline. Adrenaline is released during exercise to help make more glucose available to the exercising muscles.

  2. A rise in blood glucose during exercise is more likely if your blood glucose is already high when you start to exercise and there is very little insulin on board. When too little insulin is on board, there is no way for glucose to get into the cells where it is needed to fuel the activity. The cells are now starved for fuel. This signals the liver to produce more glucose. The glucose is released by the liver but can't get into the cells because of the low level of insulin. Blood glucose continues to rise. Even though the blood glucose is so high, the cells still can't get the fuel for energy. So they start burning fat. Ketones are then produced.


Original posting 24 Aug 97


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Last Updated: Tuesday April 06, 2010 15:08:54
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